package servlet;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(description = "downloadfilesProcess", urlPatterns = { "/downloadfilesServlet" })
public class downfilesServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public downfilesServlet() {
		super();
	}

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//filename格式  &&filename=xxx,xxx,xxx,xxx
		String fname = request.getParameter("filename");
        fname=URLDecoder.decode(fname,"UTF-8");
		String[] filenames = fname.split(",");
		List<File> files = new ArrayList<File>();
		
		for(int i=0;i<filenames.length;i++){
			String fullFilePath = this.getServletContext().getRealPath("/upload") +"/"+ filenames[i];
			files.add(new File(fullFilePath));
		}
		String finalfile = this.getServletContext().getRealPath("/upload") +"/"+"filesDownLoad.zip";
        File file = new File(finalfile);  
        // 路径为文件且不为空则进行删除  
        if (file.isFile() && file.exists()) {  
            file.delete();  
        } 
		try {
			downLoadFiles(files,finalfile,request,response);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		
		


        
  	}
	
	 public static HttpServletResponse downLoadFiles(List<File> files,String finalfile,
	            HttpServletRequest request, HttpServletResponse response)
	            throws Exception {
	        try {
	            /**这个集合就是你想要打包的所有文件，
	             * 这里假设已经准备好了所要打包的文件*/
	            //List<File> files = new ArrayList<File>();
	     
	            /**创建一个临时压缩文件，
	             * 我们会把文件流全部注入到这个文件中
	             * 这里的文件你可以自定义是.rar还是.zip*/
	    		File file = new File(finalfile);
	            if (!file.exists()){   
	                file.createNewFile();   
	            }
	            response.reset();
	            //response.getWriter()
	            //创建文件输出流
	            FileOutputStream fous = new FileOutputStream(file);   
	            /**打包的方法我们会用到ZipOutputStream这样一个输出流,
	             * 所以这里我们把输出流转换一下*/
	           ZipOutputStream zipOut 
	            = new ZipOutputStream(fous);
	            /**这个方法接受的就是一个所要打包文件的集合，
	             * 还有一个ZipOutputStream*/
	           zipFile(files, zipOut);
	            zipOut.close();
	            fous.close();
	           return downloadZip(file,response);
	        }catch (Exception e) {
	                e.printStackTrace();
	            }
	            /**直到文件的打包已经成功了，
	             * 文件的打包过程被我封装在FileUtil.zipFile这个静态方法中，
	             * 稍后会呈现出来，接下来的就是往客户端写数据了*/
	           
	     
	        return response ;
	    }

	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}
	
    public static void zipFile(List files,ZipOutputStream outputStream) {
    	int size = files.size();
    	for(int i = 0; i < size; i++) {
    		File file = (File) files.get(i);
    		zipFile(file, outputStream);
    		}
    	}
	
	public static void zipFile(File inputFile,
            ZipOutputStream ouputStream) {
        try {
            if(inputFile.exists()) {
                /**如果是目录的话这里是不采取操作的，
                 * 至于目录的打包正在研究中*/
                if (inputFile.isFile()) {
                    FileInputStream IN = new FileInputStream(inputFile);
                    BufferedInputStream bins = new BufferedInputStream(IN, 512);
                    //org.apache.tools.zip.ZipEntry
                    ZipEntry entry = new ZipEntry(inputFile.getName());
                    ouputStream.putNextEntry(entry);
                    // 向压缩文件中输出数据   
                    int nNumber;
                    byte[] buffer = new byte[512];
                    while ((nNumber = bins.read(buffer)) != -1) {
                        ouputStream.write(buffer, 0, nNumber);
                    }
                    // 关闭创建的流对象   
                    bins.close();
                    IN.close();
                } else {
                    try {
                        File[] files = inputFile.listFiles();
                        for (int i = 0; i < files.length; i++) {
                            zipFile(files[i], ouputStream);
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
	
    public static HttpServletResponse downloadZip(File file,HttpServletResponse response) {
        try {
        // 以流的形式下载文件。
        InputStream fis = new BufferedInputStream(new FileInputStream(file.getPath()));
        byte[] buffer = new byte[fis.available()];
        fis.read(buffer);
        fis.close();
        // 清空response
        response.reset();

        OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
        response.setContentType("application/octet-stream");

//如果输出的是中文名的文件，在此处就要用URLEncoder.encode方法进行处理
        response.setHeader("Content-Disposition", "attachment;filename=" +URLEncoder.encode(file.getName(), "UTF-8"));
        toClient.write(buffer);
        toClient.flush();
        toClient.close();
        } catch (IOException ex) {
        ex.printStackTrace();
        }finally{
             try {
                    File f = new File(file.getPath());
                    f.delete();
                } catch (Exception e) {
                    e.printStackTrace();
                }
        }
        return response;
    }

}
